The present invention relates to an ink-jet recording device which records an image by a single-pass recording method.
Usually, an ink-jet recording device repeatedly moves a recording head, with a plurality of ink-ejecting nozzles arranged thereon, in the direction different from the nozzle arrangement direction to print an image. A band of image area (band) is formed during each movement of the recording head. Repeatedly forming such bands completes the recording of the whole image.
When a high-density image with fill-in areas is recorded during such band formation, ink could be scattered depending upon the material or the surface condition of a recording medium. This event, called a xe2x80x9csplashxe2x80x9d, may cause an unevenly printed image.
A multi-pass recording method, which records one band in several passes of the head, can prevent the splash because the recording density of each pass is reduced. However, the recording speed in the multi-pass recording method is degraded.
Another method which reduces the per-dot ink ejection amount could be employed. However, reducing the ink ejection amount causes distortion of dots, that is called xe2x80x9cline steppingxe2x80x9d.
For use with the single-pass method, there are several other technologies for preventing unevenly printed images caused by splashes. One of them is to perform a VRC (Vector-to-Raster Conversion) for converting print data format from vector into raster, to check the bit-mapped image data, which is expanded in the frame memory, to find solid-drawing filled-in areas, and then to reduce the density of the area inside each filled-in area, except the filled-in boundary, in order to prevent an unevenly-printed image caused by splashes. However, checking the frame memory, which contains raster-converted print data, for finding filled-in areas on a software basis requires that the frame memory be checked one bit at a time, thus increasing the processing time. On the other hand, making this search on a hardware basis will increase the cost of the device. For this reason, this technology is not practical on a standard ink jet recording device.
Therefore, to solve the problem described above, it is an object of the present invention to provide a single-pass ink jet recording method and device capable of reducing an ink splash (splash event), which is caused when a solid-drawing area is printed, through the processing of the interpreter of the ink jet recording device which forms a fill-in data pattern and a thick line shading data pattern.
It is another object of the present invention to provide a single-pass ink jet recording method and device capable of reducing a splash event depending upon the difference in the ink jet recording devices or in the ink running characteristics of the recording medium.
An ink-jet recording method according to the present invention receives a command and data which indicate a drawing of a thick line or a filled-in area, analyzes the command and the data by an interpreter, converts vector data of the thick line or the filled-in area into raster data based on a given data pattern after the analysis, and, based on the raster data, ejects ink droplets while moving a recording head over a recording medium with a plurality of ink ejection nozzles arranged thereon, the method comprising the steps of: before converting to the raster data, checking by the interpreter whether the data pattern indicates solid-drawing in each of the thick line or the filled-in area for which the drawing is indicated; and, if the data pattern indicates solid-drawing, changing the data pattern to a lower-density pattern, thereby preventing an ink splash during printing.
This configuration allows the ink jet recording device to reduce the density of the solid-drawing area of a thick-line or a filled-in area and to reduce the splashes without having to change the processing performed on an external computer terminal and so on and without the need for searching the frame memory for filled-in areas.
The interpreter may change the data pattern, for example, using a predetermined mask pattern. This makes it easy to change the data pattern.
Preferably, one mask pattern should be selected from a plurality of predetermined mask patterns according to a type of the recording medium. This allows the density to be reduced according to the type of recording medium.
If the thickness of the thick line is smaller than a predetermined thickness, the data pattern remains unchanged which will eliminate an unnecessary process to be performed and reduce the processing load.
It is preferable that the data pattern be changed at least for black ink.
An ink-jet recording device according to the present invention comprises an interpreter for analyzing a command and data which indicate a drawing of a thick line or a filled-in area; means for converting vector data of the thick line or the filled-in area into raster data based on a given data pattern after the analysis by the interpreter; and a recording head for ejecting ink droplets, based on the raster data, while moving over a recording medium with a plurality of ink ejection nozzles arranged thereon, wherein the interpreter includes a pattern changing means for checking whether the data pattern indicates solid-drawing in each of the thick line or the filled-in area for which the drawing is indicated and, if the solid-drawing is indicated, changing the data pattern to a lower-density pattern.
The data pattern changing means may change the data pattern by using a predetermined mask table which stores therein a predetermined mask pattern.
Preferably, the predetermined mask table contains a plurality of mask patterns each corresponding to a type of the recording medium and the pattern changing means selects one of the mask patterns according to the type of the recording medium used.
The present invention is suitable for an ink jet recording method and device employing a single-pass recording method.